Safety valves are devices commonly used in installations utilizing various apparatus for the storage and handling of fluids. When a high level of reliability is required of such installations, for example in the case of nuclear power stations, it is indispensable to make certain of the correct operation of all components, particularly the safety valves. It is therefore appropriate to install on these valves devices detecting their operation.
Detection devices of this kind may comprise a detection means which is displaced at the same time as the movable portion of the valve carrying the valve closure means.
It is then possible to detect the displacement of the movable part of the valve, or else the closure or opening of the latter, by monitoring the displacements or the position of the movable detection means.
However, these extremely simple devices, which are also extremely reliable because they follow the displacements of the movable part of the valve, with which they are generally in direct contact, are not entirely satisfactory because they require the fitting to the valve of detection means which are liable to hinder the correct operation of the valve itself and consequently entail a reduction of the reliability of the valve.